Count in factors: Difference between revisions
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m (→{{header|REXX}}: added highlights and whitespace in the REXX section header. -- ~~~~) |
(→{{header|REXX}}: used "internal" type subroutine name, removed superfluous STRIP invocation, changed statement indentation, added whitespace, change/added comments. -- ~~~~) |
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<br><br>Also, as per the task's requirements, the prime factors of '''1''' (unity) will be listed as '''1''', |
<br><br>Also, as per the task's requirements, the prime factors of '''1''' (unity) will be listed as '''1''', |
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<br>even though, strictly speaking, it should be '''null'''. |
<br>even though, strictly speaking, it should be '''null'''. |
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<lang rexx>/*REXX program |
<lang rexx>/*REXX program finds and lists the prime factors of positive integer(s).*/ |
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numeric digits |
numeric digits 12 /*bump precision of the numbers. */ |
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parse arg low high . /*get the argument(s) |
parse arg low high . /*get the argument(s) from the CL*/ |
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if high=='' then high=low |
if high=='' then high=low /*No HIGH? Then make one up. */ |
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w=length(high) /*get max width for pretty tell. */ |
w=length(high) /*get max width for pretty tell. */ |
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blanks=1 /*allow spaces around the |
blanks=1 /*allow spaces around the "x". */ |
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do n=low to high /*process single number | a range*/ |
do n=low to high /*process single number | a range*/ |
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say right(n,w) '=' space(factr(n),blanks) /*display N & factors*/ |
say right(n,w) '=' space(factr(n),blanks) /*display N & factors*/ |
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exit /*stick a fork in it, we're done.*/ |
exit /*stick a fork in it, we're done.*/ |
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/*──────────────────────────────────FACTR subroutine────────────────────*/ |
/*──────────────────────────────────FACTR subroutine────────────────────*/ |
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factr: procedure; parse arg x 1 z /*defines X and Z from the arg. |
factr: procedure; parse arg x 1 z /*defines X and Z from the arg.*/ |
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if x <1 then return '' /* |
if x <1 then return '' /*Invalid number? Return null. */ |
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if x==1 then return 1 /*special case for unity. |
if x==1 then return 1 /*handle special case for unity. */ |
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| ⚫ | |||
Xtimes= 'x' /*character used for "times" (x).*/ |
Xtimes= 'x' /*character used for "times" (x).*/ |
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list= /*nullify the list (to empty). */ |
list= /*nullify the list (to empty). */ |
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do j=2 to 5; if j\==4 then call buildF; end |
do j=2 to 5; if j\==4 then call .buildF; end /*fast builds for list.*/ |
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j=5 /*start were we left off (five).*/ |
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| ⚫ | |||
do y=0 by 2; j=j+2+y//4 /*insure it's not divisible by 3.*/ |
do y=0 by 2; j=j+2+y//4 /*insure it's not divisible by 3.*/ |
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if right(j,1)==5 then iterate /*fast check for divisible by 5.*/ |
if right(j,1)==5 then iterate /*fast check for divisible by 5.*/ |
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if j>z then leave /*number reduced to a small 'un? */ |
if j>z then leave /*number reduced to a small 'un? */ |
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if j*j>x then leave /*are we higher than the √ of X ?*/ |
if j*j>x then leave /*are we higher than the √ of X ?*/ |
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call buildF |
call .buildF /*add a prime factor to list (J).*/ |
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end /*y*/ |
end /*y*/ |
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if z==1 then z= /*if residual is = 1, nullify it.*/ |
if z==1 then z= /*if residual is = 1, nullify it.*/ |
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return |
return strip(strip(list Xtimes z),,Xtimes) /*elide any leading "x". */ |
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/*──────────────────────────────────.BUILDF subroutine──────────────────*/ |
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/*──────────────────────────────────BUILDF subroutine───────────────────*/ |
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buildF: do while z//j==0 |
.buildF: do while z//j==0 /*keep dividing until it hurts. */ |
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list=list Xtimes j |
list=list Xtimes j /*add number to the list (J). */ |
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z=z%j |
z=z%j /*do an integer divide. */ |
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end /*while*/ |
end /*while*/ |
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return</lang> |
return</lang> |
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'''output''' when using the input of: <tt> 1 30 </tt> |
'''output''' when using the input of: <tt> 1 30 </tt> |
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